System and Method for Resource Management in a Communications System

ABSTRACT

A method for operating a communications controller includes defining a positive integer quantity of resource element groups from a resource block with a positive integer number N resource elements in each resource element group, the resource block having a total number of resource elements, the total number of resource elements consisting of available resource elements and reserved resource elements. The method also includes assigning a plurality of available resource elements to fill in each of the positive integer quantity of resource element groups with N available resource elements in each resource element group, and blocking any unassigned available resource elements from being used in a resource element group. The method further includes interleaving a plurality of control messages onto the positive integer quantity of resource element groups, and transmitting the positive integer quantity of resource element groups.

This application is a continuation of U.S. Non-Provisional applicationSer. No. 14/599,119, filed Jan. 16, 2015, entitled “Time-To-DigitalConverter in Phase-Locked Loop”, which is a continuation of U.S.Non-Provisional application Ser. No. 13/296,434, filed Nov. 15, 2011,entitled “System and Method for Resource Management in a CommunicationsSystem,” now U.S. Pat. No. 8,959,361, issued on Feb. 17, 2015, whichclaims the benefit of U.S. Provisional Application Ser. No. 61/413,820,filed on Nov. 15, 2010, entitled “Resource-Element Groups for R-PDCCH,”all of which applications are hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to digital communications, andmore particularly to a system and method for resource management in acommunications system.

BACKGROUND

Evolved Universal Mobile Telecommunications System (UMTS) TerrestrialRadio Access Network (e-UTRAN or EUTRAN) is an air interface of TheThird Generation Partnership (3GPP) Long Term Evolution (LTE) upgradepath for mobile communications systems. e-UTRAN is also known as EvolvedUniversal Terrestrial Radio Access (E-UTRA) in early drafts of 3GPP LTE.3GPP LTE Release-10 introduces to the standard several LTE Advanced(LTE-A) features like carrier aggregation, uplink (UL) Single UserMultiple Input Multiple Output (SU-MIMO), relay nodes, and the like,aiming to provide a considerable peak data rate increase.

A downlink (DL), which is a unidirectional communications link from acommunications controller (commonly referred to as a base station, aNodeB, an enhanced NodeB, a controller, a cell, a macro cell a low powercell, and the like) to a communications device (such as a relay node, ora mobile station, also commonly referred to as a User Equipment, user,subscriber, terminal, and the like), includes several control channels.The control channels include a Physical Downlink Control Channel (PDCCH)that carries, among other information, the DL allocation information andUL allocation grants for the communications device. While the PhysicalControl Format Indicator Channel (PCFICH) is used to signal the lengthof the PDCCH. The Physical Hybrid ARQ Indicator Channel (PHICH) used tocarry the acknowledgments from the uplink transmissions. The PhysicalDownlink Shared Channel (PDSCH) is used for L1 transport datatransmission. Supported modulation formats on the PDSCH are QPSK, 16QAMand 64QAM. The Physical Multicast Channel (PMCH) is used for broadcasttransmission using a Single Frequency Network. The Physical BroadcastChannel (PBCH) is used to broadcast the basic system information withinthe cell.

SUMMARY OF THE INVENTION

Example embodiments of the present invention which provide a system andmethod for resource management in a communications system.

In accordance with an example embodiment of the present invention, amethod for operating a communications controller is provided. The methodincludes defining a positive integer quantity of resource element groupsfrom a resource block with a positive integer number N resource elementsin each resource element group, the resource block having a total numberof resource elements, the total number of resource elements consistingof available resource elements and reserved resource elements, assigninga plurality of available resource elements to fill in each of thepositive integer quantity of resource element groups with N availableresource elements in each resource element group, blocking anyunassigned available resource elements from being used in a resourceelement group, interleaving a plurality of control messages onto thepositive integer quantity of resource element groups, and transmittingthe positive integer quantity of resource element groups.

In accordance with another example embodiment of the present invention,a method for operating a communications controller is provided. Themethod includes defining a positive integer quantity of resource elementgroups with a positive integer number N resource elements in eachresource element group, determining a positive integer quantity ofresource blocks necessary for providing sufficient available resourceelements to fill each resource element group with N available resourceelements, a total number of resource elements across the positiveinteger quantity of resource blocks consisting of available resourceelements and reserved resource elements prohibited from being assignedto a resource element group, assigning all available resource elementsto the positive integer quantity of resource element groups,interleaving a plurality of control messages onto the positive integerquantity of resource element groups, and transmitting the positiveinteger quantity of resource element groups.

In accordance with another example embodiment of the present invention,a method for operating a communications device is provided. The methodincludes receiving a resource block including a plurality of controlmessages interleaved within a positive integer quantity of resourceelement groups defined from the resource block with a positive integernumber N resource elements in each resource element group, the resourceblock having a total number of resource elements, the total number ofresource elements consisting of available resource elements, reservedresource elements, and blocked available resource elements remainingafter assigning a plurality of available resource elements to fill ineach of the positive integer quantity of resource element groups with Navailable resource elements in each resource element group,de-interleaving the plurality of control messages from the receivedresource block, and selecting a control message for the communicationsdevice from the plurality of control messages.

In accordance with another example embodiment of the present invention,a method for operating a communications device is provided. The methodincludes receiving a positive integer quantity of resource blocksincluding a plurality of control messages interleaved within a positiveinteger quantity of resource element groups with a positive integer Nresource elements in each resource element group, the positive integerquantity of resource blocks providing sufficient available resourceelements to fill each resource element group with N available resourceelements, a total number of resource elements across the positiveinteger quantity of resource blocks consisting of available resourceelements and reserved resource elements prohibited from being assignedto a resource element group, de-interleaving the plurality of controlmessages from the received positive integer quantity of resource blocks,and selecting a control message for the communications device from theplurality of control messages.

In accordance with another example embodiment of the present invention,a communications controller is provided. The communications controllerincludes a processor, and a transmitter coupled to the processor. Theprocessor defines a positive integer quantity of resource element groupswith a positive integer number N resource elements in each resourceelement group, and determines a positive integer quantity of resourceblocks necessary for providing sufficient available resource elements tofill each resource element group with N available resource elements, atotal number of resource elements across the positive integer quantityof resource blocks consisting of available resource elements andreserved resource elements prohibited from being assigned to a resourceelement group. The processor also assigns all available resourceelements to the positive integer quantity of resource element groups,and interleaves a plurality of control messages onto the positiveinteger quantity of resource element groups. The transmitter transmitsthe positive integer quantity of resource element groups.

In accordance with another example embodiment of the present invention,a communications device is provided. The communications device includesa receiver, and a processor coupled to the receiver. The receiverreceives a resource block including a plurality of control messagesinterleaved within a positive integer quantity of resource elementgroups defined from the resource block with a positive integer number Nresource elements in each resource element group, the resource blockhaving a total number of resource elements, the total number of resourceelements consisting of available resource elements, reserved resourceelements, and blocked available resource elements remaining afterassigning a plurality of available resource elements to fill in each ofthe positive integer quantity of resource element groups with Navailable resource elements in each resource element group. Theprocessor de-interleaves the plurality of control messages from thereceived resource block, and selects a control message for thecommunications device from the plurality of control messages.

One advantage of example embodiments disclosed herein is that completeresource element groups (REG) are defined for a variety of overheadconfigurations, including resource elements reserved for referencesignals, muted resource elements, and the like. Therefore, defining andusing REGs are simpler.

A further advantage of example embodiments is that a consistentdefinition of REGs is used, thereby maintaining consistency with early3GPP LTE releases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawing, in which:

FIG. 1a illustrates an example communications system according toexample embodiments described herein;

FIG. 1b illustrates an example subframe according to example embodimentsdescribed herein;

FIG. 1c illustrates an example subframe with two second control regionsaccording to example embodiments described herein;

FIG. 2 illustrates an example flow diagram of communications controlleroperations in transmitting control messages according to exampleembodiments described herein;

FIG. 3a illustrates an example RB where there are a number of REsreserved for carrying Common Reference Signals according to exampleembodiments described herein;

FIG. 3b illustrates an example RB where there are a number of REsreserved for carrying CRS and/or CSI-RS according to example embodimentsdescribed herein;

FIG. 4 illustrates an example RB where there are a number of REsreserved for carrying CRS and/or CSI-RS as well as some that are usedfor muted CSI-RS according to example embodiments described herein;

FIGS. 5a-5d illustrate example configurations for specifying REGs fromREs over two RBs according to example embodiments described herein;

FIGS. 6a-6e illustrate example configurations for specifying REGs fromREs over one RB according to example embodiments described herein;

FIGS. 7a and 7b illustrate example first configurations for specifyingREGs from REs with four and eight CSI-RS ports according to exampleembodiments described herein;

FIGS. 8a and 8b illustrate example second configurations for specifyingREGs from REs with four and eight CSI-RS ports according to exampleembodiments described herein;

FIG. 9 illustrates an example third configuration for specifying REGsfrom REs with eight CSI-RS ports according to example embodimentsdescribed herein;

FIG. 10 illustrates an example flow diagram of communications controlleroperations in interleaving multiple control messages, such as R-PDCCHs,to REGs of one or more RBs according to example embodiments describedherein;

FIG. 11 illustrates an example flow diagram of operations at a device asthe device receives and processes interleaved control messages accordingto example embodiments described herein;

FIG. 12 illustrates an example communications controller according toexample embodiments described herein; and

FIG. 13 illustrates an example communications device according toexample embodiments described herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The operating of the current example embodiments and the structurethereof are discussed in detail below. It should be appreciated,however, that the present invention provides many applicable inventiveconcepts that can be embodied in a wide variety of specific contexts.The specific embodiments discussed are merely illustrative of specificstructures of the invention and ways to operate the invention, and donot limit the scope of the invention.

One embodiment of the invention relates to improving communicationsperformance by interleaving multiple messages together. The interleavingof the multiple transmissions may be based on groups of four resourceelements, each referred to as a resource element group (REG). The REGsare defined over multiple resource blocks to ensure that there are aninteger number of REGs after excluding resource elements that arereserved for transmitting reference signals, muted resources elements,prevented from use in a REG, and the like. In another embodiment, theREGS are defined over a single resource block with resource elementsthat are prohibited from being used in REGs added to ensure that therean integer number of REGs. For example, the REGs may be defined over tworesource blocks to ensure that an integer number of REGs are availablefor interleaving transmissions even when resource elements are or arenot reserved for transmitting reference signals, zero power referencesignals, and the like.

The present invention will be described with respect to exampleembodiments in a specific context, namely a 3GPP LTE compliantcommunications system. The invention may also be applied, however, toother standards compliant communications systems, such as IEEE 802.16,WiMAX, and the like, or non-standards compliant communications systemsthat support interleaving transmissions where the transmissions areinterleaved based on interleaving resources that are larger than afundamental transmission resource.

FIG. 1a illustrates a communications system 100. Communications system100 includes an enhanced NodeB (eNB) 105, a relay node (RN) 110, a firstUser Equipment (UE) 115, and a second UE 120. While it is understoodthat communications systems may employ multiple eNBs capable ofcommunicating with a number of UEs, only one eNB, two UEs, and one RNare illustrated for simplicity.

A RN is considered as a tool to improve, e.g., the coverage area of highdata rate communications, group mobility, temporary network deployment,the cell-edge throughput, and/or to provide coverage in new areas. TheRN is wirelessly connected to a wireless communications network via aneNB, such as eNB 105.

UE 115 and UE 120 may be a communications device that may allow anoperator to connect to a service, such as voice service, data service,multimedia service, and the like. As shown in FIG. 1, eNB 105 hasallocated some resources to RN 110, which in turn, may allocate someresources (provided by eNB 105) to UE 120. eNB 105 may also directlycommunicate with UEs. For example, eNB 105 directly allocates resourcesto UE 115. Communications between eNB 105 and RN 110 may be made over acommunications link (uplink and/or downlink directions) referred to as aUn link 120 or a wireless backhaul link, while communications between RN110 and UE 120 may be made over a communications link (uplink and/ordownlink directions) referred to as a Uu link 130 or an access link.Communications between eNB 105 and UE 115 may be made overcommunications link referred to as access link 135.

FIG. 1b illustrates a subframe 150. Subframe 150 comprises a firstcontrol region 155 and a data region 160. Subframe 150 shows an examplefor a multicarrier modulation system. Subframe 150 may also be referredto as a resource block (RB) or a resource block pair. As discussedabove, the first control region 155 may include control signaling, suchas a Physical Downlink Control Channel (PDCCH), while data region 160may include data (shown as a Physical Downlink Shared Channel (PDSCH) aswell as control signaling, which may include the Relay-Physical DownlinkControl Channel (R-PDCCH), as well as new control channels, such as aUser Physical Hybrid Automatic Repeat Requested Indicator Channel(U-PHICH) or a User Physical Downlink Control Channel (U-PDCCH). Notethat the representation on FIG. 1b is in the logical domain, and may notnecessarily map with actual allocated physical resources.

First control region 155 may also be called a PDCCH control region. Thecontrol channels are located in a second control region 165, which maybe inside data region 160. Second control region 165 may comprise theR-PDCCH, as well as an extension for UEs (also called the U-PDCCHcontrol region) as well as frequency domain extensions of the PDCCH,such as extended PDCCH (E-PDCCH or ePDCCH). As shown in FIG. 1b , secondcontrol region 165 is located in data region 160, while PDCCH is locatedin first control region 155.

Although the discussion of the example embodiments focuses on theR-PDCCH, the example embodiments may be operable with other controlchannels, such as the U-PDCCH, frequency domain extensions of the PDCCH,and the like. Therefore, the discussion of the R-PDCCH should not beconstrued as being limiting to either the scope or the spirit of theexample embodiments.

Generally the data region can start from OFDM symbol 1, 2, 3, or 4, andthe second control region can also start from these values. When thedata region can start from OFDM symbol zero, the control channel in thedata region can then also start from OFDM symbol zero, in thissituation, the first control region may disappear.

The representation of the various channels and regions in FIG. 1b islogical in nature with no direct relationship to an actual mapping ofspecific physical resources. In particular, the resources comprisingsecond control region 165 may be distributed in frequency and are notrestricted to be contiguous in frequency. Second control region 165 mayalso be time multiplexed with data, and for instance, may occupy onlythe first or the second slot or both the first and the second slot of asubframe. In addition, second control region 165 may not necessarilystart immediately after first control region 155, but may be offset byone or more symbols. Second control region 165 may consist of PhysicalRBs (PRBs) or Virtual RBs (VRBs), either localized or distributed.

FIG. 1c illustrates a subframe 175. Subframe 175 comprises a firstcontrol region 180 and a data control region 185. Subframe 150 may alsobe referred to as a RB pair. Data region 185 may differ from data region160 shown in FIG. 160 in that data region 185 is partitioned into twosecond control regions, which may be referred to as half of a RB (HRB).Data region 185 may consist of half of a Physical RB (HPRB) or half of aVirtual RB (HVRB), either localized or distributed. A HRB can be half ofa RB or RB pair. A HPRB can be half of a PRB or half of a PRB pair, anda HVRB can be half of a VRB or half of a VRB pair. In a manner similarto how a RB covers an entire slot, and a RB pair covers an entiresubframe in the time domain, the HRB, HPRB, and/or HVRB can cover oneslot or the whole subframe in the time domain (i.e., two HRB pair, twoHPRB pair, and/or two HVRB pair).

When data region 185 is referred to as comprising a HRB, a HPRB, or aHVRB, then data region 185 already excludes first control region 185.Although data region 185 is shown in FIG. 1c as being partitioned intotwo equal second control regions, data region 185 may be partitionedinto any number of second control regions and the second control regionsneed not be equal in size. Furthermore, data region 185 may also includedata, e.g., one of the HRBs is used for control, and anther HRB is usedfor data.

In 3GPP LTE compliant communications systems, R-PDCCHs (as well as othercontrol channels) can be either cross interleaved (or simplyinterleaved) or not cross interleaved (or simply not interleaved). Withcross interleaving, a set of two or more R-PDCCHs may be multiplexedtogether. Each of the R-PDCCHs in the set is transmitted on anaggregation of one or several consecutive control channel elements(CCEs), where a control channel element corresponds to a number of, forexample, nine, resource element groups (REG). The REGs for variousR-PDCCHs are multiplexed and cross interleaved together. With no crossinterleaving, each R-PDCCH is transmitted separately on the assignedresources for that R-PDCCH. It is noted that the terms crossinterleaving and interleaving may be used interchangeably herein.

On a Un link (for example, Un link 120), a RN (e.g., RN 110) may beinformed by an eNB (such as eNB 105) about transmissions using aR-PDCCH. Transmissions to multiple users in the R-PDCCH may beinterleaved (e.g., mode 1-1) or non-interleaved. For interleavedtransmissions, an interleaver similar to an interleaver used for a PDCCHin 3GPP LTE Release-8 is used. In particular, an interleaving resourcedefined as a REG is used. A single REG consists of four resourceelements (RE) of a single symbol in a single resource block (RB), forexample.

However, unlike a PDCCH, which is transmitted in a control region of atransmission subframe (e.g., first control region 155), the R-PDCCH istransmitted in a data region (for example, data region 160) of thetransmission subframe and may be used to also transmit referencesignals, such as a Demodulation Reference Signal (DMRS), Channel StateInformation Reference Signal (CSI-RS), muted CSI-RS, unmuted CSI-RS, andthe like, which consume REs.

Therefore, the definition of a REG for the R-PDCCH is not as clear cutas the definition of a REG for the PDCCH. In particular, the overhead ofthe DMRS and the CSI-RS needs to be eliminated from the RB in thedefinition of a REG. Furthermore, some REs need to be muted (muting canmean zero or reduced power transmission) on some antenna portconfigurations. When the REs that are to be muted are eliminated, thenumber of REs in a RB (or in a symbol of a RB) available forinterleaving is not always a multiple of four. Hence, there may be anon-integer number of REGs in a RB, thus making the definition of a REGnot straightforward. So, there is a need for a system and method forresource management in a communications system.

FIG. 2 illustrates a flow diagram of communications controlleroperations 200 in transmitting control messages. Communicationscontroller operations 200 may be indicative of operations occurring in acommunications controller, such as an eNB, a low power node, and thelike, as the communications controller transmits control messages torecipients, such as RNs, UEs, and the like, wherein the messages areinterleaved. Communications controller operations 200 may also beindicative of operations occurring in a communications controllertransmitting control messages to RNs. Communications controlleroperations 200 may apply to the transmission of control messages, suchas R-PDCCHs, U-PHICHs, U-PDCCHs, E-PDCCH, ePDCCH, and the like.

Communications controller operations 200 may begin with thecommunications controller preparing control messages for transmission(block 205). For discussion purposes, consider a situation wherein acommunications controller is transmitting control messages, such asR-PDCCHs, to RNs. Although the discussion focuses on the transmitting ofR-PDCCHs to RNs, the example embodiments discussed herein may beapplicable to other types of control messages (such as U-PHICHs,U-PDCCHs, E-PDCCH, ePDCCH, and the like) transmitted to othercommunications devices, such as UEs. Therefore, the discussion ofR-PDCCHs and RNs should not be construed as being limiting to either thescope or the spirit of the example embodiments.

In general, the preparation of control messages for transmission mayinvolve multiple operations, including, but not limited to: generatingcontrol data, selection of a modulation and coding scheme (MCS) (as wellas an aggregation level if needed), and encoding.

Typically, there is a separate R-PDCCH for each RN coupled to thecommunications controller. According to an example embodiment, controldata to be included in an R-PDCCH may include resource assignment, MCSinformation, Hybrid Automatic Repeat Request (HARQ) information, and thelike.

The communications controller may select a MCS and/or aggregation levelfor each R-PDCCH. The communications controller may select a MCS foreach R-PDCCH in accordance with a set of selection criteria. Possiblemodulation techniques may include QPSK, 16-QAM, 64-QAM, or any othermodulation technique. The coding rate selected may be chosen, dependingwhich modulation technique is used, so that the RN may receive itsR-PDCCH with a reasonable probability of successful decoding. Theaggregation level, which specifies allocated bandwidth for the R-PDCCH,may also impact MCS. In addition, the communications controller mayselect to use spatial multiplexing. The MCS and/or the aggregation levelselected for the various RNs may be different for each RN, identical theRNs, or a combination thereof.

Examples of the set of selection criteria may include amount of controldata to be transmitted, amount of network resources available perR-PDCCH, operating environment, communications system load, a quality ofthe communications channel between the eNB and the RNs, and the like.

With the MCS and/or the aggregation level selected for each RN, thecommunications controller may encode each R-PDCCH in accordance with itsselected MCS and/or selected aggregation level. However, the encodingmay also be performed in accordance to other factors, includingpermissible codes, data rates, and the like.

With the control messages prepared, the communications controller maygenerate the control messages (block 210). Since there are multiplecontrol messages, the generating of the control messages may include thecommunications controller processing the multiple control messages(e.g., the multiple R-PDCCHs), which may involve the communicationscontroller interleaving the multiple R-PDCCHs or not interleaving themultiple R-PDCCHs.

In general, interleaving the multiple R-PDCCHs may include thecommunications controller assigning each R-PDCCHs of a subset of themultiple R-PDCCHs to one or more REGs of one or more RBs and thenplacing the assigned R-PDCCHs into the REs of the REGs. The assigning ofthe R-PDCCHs to the REGs may be based on an interleaving rule or aninterleaving function, which may assign the R-PDCCHs with intent inspreading out the information in the R-PDCCHs to help improve toleranceto errors, frequency diversity, and the like. Interleaving (assigningand then placing) the multiple R-PDCCHs may also be referred to asmapping the multiple R-PDCCHs based on the interleaving rule.

For discussion purposes, considering a situation wherein thecommunications controller interleaves the multiple R-PDCCHs. Asdiscussed previously, each of the R-PDCCHs may be interleaved on a REG(a group of four REs, for example) basis, wherein an R-PDCCH be assignedto one or more REGs of one or more RBs. The communications controllermay assign the R-PDCCHs to the REGs until all of the R-PDCCHs have beenassigned or all of the REGs available for use have been assigned.

In some situations, a R-PDCCH may be larger (in terms of informationcontent) than the data capacity of a single REG. In such a situation,the R-PDCCH may be partitioned into multiple units, which may then beassigned to a REG. Generally, the units may be the size (in terms ofinformation capacity) of a REG or as close to the size of a REG aspossible. Furthermore, if a R-PDCCH is not an integer multiple of a REGin size, then the R-PDCCH may be partitioned into as many REG sizedunits as possible with one unit that is not REG sized.

The REGs that are available for the communications controller to assignto the transmission of the R-PDCCHs may be defined from REs of RBs basedon rules, commonly referred to as principles. In general, REGs may bedefined from a plurality of REs of RBs that are available for use totransmit the R-PDCCHs, where a RB comprises a number of REs, some ofwhich may be available for use to transmit the R-PDCCHs and some ofwhich may not be available for use to transmit the R-PDCCHs. As anexample, some REs may be reserved for transmitting CRS, CSI-RS, mutedCSI-RS, and the like, and may not be used to transmit the R-PDCCHs.Hence, these REs may be prohibited from use in a REG. The reserved REsmay be reserved for transmitting these signals (CRS, CSI-RS, mutedCSI-RS, and the like) according to a technical standard, such as forcompliance to a 3GPP LTE standard.

In order to maximize resource utilization, the REGs may be defined fromthe REs so that as many of the REs available for use in transmitting theR-PDCCHs are used to form REGs as possible. As an example, REs that areavailable for transmitting the R-PDCCHs but are not used to define theREGs may remain unused, thereby reducing the overall resourceutilization and efficiency of the communications system. A detaileddiscussion of principles used to allocate REGs from REs of RBs isprovided below.

The communications controller may perform rate matching as part ofgenerating the control messages. Rate matching may also help to increasenetwork resource utilization so that there is little or no networkresource waste. Rate matching may help to ensure that REs of a RB areoccupied by matching a rate of the R-PDCCH with the rate of the REs ofthe RBs, thereby reducing or eliminating resource waste. Rate matchingmay be optional. According to an example embodiment, rate matching maybe performed for the R-PDCCHs on an individual basis.

The communications controller may transmit the interleaved controlmessages (block 215). The transmitting of the interleaved controlmessages may include mapping the RBs or REGs to physical resource blocksand then actually transmitting the physical resource blocks.Transmitting the interleaved control messages may also include digitalto analog conversion, signal amplification, filtering, and the like.

As discussed above, the definition of a REG from REs of a RB for use intransmitting R-PDCCHs may not be as clear cut as the definition of a REGfor use in transmitting PDCCHs since REs that may be used intransmitting R-PDCCHs may also be used for the transmission of DMRS,CSI-RS, muted CSI-RS, and the like, and need to be eliminated from a setof available REs (of a RB or RBs) that may be used to define REGs.

When there is no CSI-RS muting, the REG definition is based on thefollowing principle (referred to herein as principle P):

The REG used for R-PDCCH includes four consecutive REs in one OFDMsymbol after discounting the REs used for CRS and CSI-RS, whenappropriate.

FIG. 3a illustrates a RB 300 where there are a number of REs reservedfor carrying Common Reference Signals (CRS). RB 300 comprises a block ofREs arranged in a 14 by 12 block of REs. Some of the REs may be reservedfor carrying a CRS, such as RE 305, while other REs may be used to carrydata, such as RE 310. A REG 315 may be specified from four consecutiveREs when there are four consecutive REs that may be used to carry dataare available, as specified in principle P. A REG 320 may be specifiedfrom four non-consecutive REs when a number of REs reserved for carryinga CRS is present. Using the four RE definition of a REG as shown inprinciple P allows for an integer number of REGs in a RB when there areREs reserved for CRS transmission.

FIG. 3b illustrates a RB 350 where there are a number of REs reservedfor carrying CRS and/or CSI-RS. Some of the REs may be reserved forcarrying a CRS, such as RE 355, while other REs may be used to carrydata, such as RE 360, and yet other REs may be used to carry CSI-RS,such as RE 365. A REG 370 may be specified from four consecutive REswhen there are four consecutive REs that may be used to carry data areavailable, as specified in principle P. A REG 375 may be defined fromfour non-consecutive REs when a number of REs reserved for carrying aCRS is present. A REG 380 may be specified from four non-consecutive REswhen a number of REs reserved for carrying a CSI-RS is present. Usingthe four RE definition of a REG as shown in principle P allows for aninteger number of REGs in a RB when there are REs reserved for CRSand/or CSI-RS transmission.

FIG. 4 illustrates a RB 400 where there are a number of REs reserved forcarrying CRS and/or CSI-RS as well as some that are used for mutedCSI-RS. Some of the REs may be reserved for carrying a CRS, such as RE405, while other REs may be used to carry data, such as RE 410, and yetother REs may be used to carry CSI-RS, such as RE 415. While other REsmay be used to carry non-muted CSI-RS, such as RE 420. In general, amuted CSI-RS may also be referred to as a zero power CSI-RS, while anon-muted CSI-RS (or simply CSI-RS) may be referred to as a non-zeropower CSI-RS. The terminology may be used interchangeably without lossof generality.

In general, a REG may be defined in a column order and if an end of acolumn is reached before a REG is complete, then REs from the nextcolumn are used. As an example, a REG 425 may be specified from fourconsecutive REs when there are four consecutive REs that may be used tocarry data are available, as specified in principle P. Similarly, REG430 may be specified from four non-consecutive REs when a number of REsreserved for carrying a CRS is present. A REG 435 may be specified fromfour non-consecutive REs when a number of REs reserved for carrying amuted CSI-RS (zero power CSI-RS) is present. A REG 440, which starts atthe bottom of column 10 and continues to the top of column 11, may bespecified from four non-consecutive REs when a number of REs reservedfor carrying a CSI-RS (non-zero power CSI-RS) is present.

However, utilizing principle P when muted CSI-RS (zero power CSI-RS) arepresent results in two REs (shown as REs 445) remaining undefined aspart of a REG. Hence, the REs 445 may be wasted unless two additionalREs (RE 450 and RE 452, for example) are found and defined along withREs 445 to form another REG.

According to an example embodiment, the definition of REGs may bemodified so that a REG may be defined over two RBs in order to ensurethat all REs are defined as REGs. The definition of a REG over two RBsmay be expressed as principle (referred to herein as principle P′):

The REG used for R-PDCCH includes four consecutive REs after discountingthe REs used for CRS, non-zero power CSI-RS, and zero power CSI-RS whenappropriate. The REGs are defined over two RBs.

Although the discussion focuses on specifying REGs over two RBs, theexample embodiments presented herein may be operable with any number ofRBs divisible by two, for example, two, four, six, eight, and the like.Therefore, the focus on two RBs should not be construed as beinglimiting to either the scope or the spirit of the example embodiments.

FIG. 5a illustrates a first configuration 500 for specifying REGs fromREs over two RBs. First configuration 500 comprises logicallyhorizontally placing the two RBs (RB 505 and RB 507 ) together to form adouble-wide RB. As an example, if a single RB was a 14 by 12 rectangulararray of REs, then the double-wide RB would be a 28 by 12 rectangulararray of REs.

Definition of REs into REGs may follow as shown in FIG. 4 (i.e., columnorder within individual RBs), resulting in two REs being undefined aspart of a REG at the end of RB 505 (shown as REs 509). However, byallowing a REG to span two RBs, REs 509 may be combined with two REs inRB 507 (shown as REs 511) to form a REG. The definition of REs into REGsmay continue with the remainder of REs in RB 507, resulting in aninteger number of REGs and no unused REs.

FIG. 5b illustrates a second configuration 525 for specifying REGs fromREs over two RBs. Second configuration 525 comprises logicallyvertically stacking two RBs (RB 530 and RB 532) together to form adouble-tall RB. As an example, if a single RB was a 14 by 12 rectangulararray of REs, then the double-tall RB would be a 14 by 24 rectangulararray of REs.

Definition of REs into REGs may follow as shown in FIG. 4 (i.e., columnorder within individual RBs), resulting in two REs being undefined aspart of a REG at the end of RB 530 (shown as REs 534). However, byallowing a REG to span two RBs, REs 534 may be combined with two REs inRB 532 (shown as REs 536) to form a REG. The definition of REs into REGsmay continue with the remainder of REs in RB 532, resulting in aninteger number of REGs and no unused REs.

FIG. 5c illustrates a third configuration 550 for specifying REGs fromREs over two RBs. Third configuration 550 comprises logically verticallystacking two RBs (RB 555 and RB 557) together to form a double-tall RB.As an example, if a single RB was a 14 by 12 rectangular array of REs,then the double-tall RB would be a 14 by 24 rectangular array of REs.

Definition of REs into REGs may differ from the allocation shown in FIG.5b . While still defined in column order, the definition of REs intoREGs as shown in FIG. 5c spans the two vertically stacked RBs (referredto herein as column order spanning multiple RBs). Instead of definingREs within a single RB into REGs until all of the RBs have been definedas in FIG. 5b , the definition of REs into REGs in FIG. 5c may beperformed vertically, crossing RB boundaries as needed. For example,consider column 3 of RB 555 where three REGs may be defined. Then, thenext REG defined would be in column 3 of RB 557 rather than in column 4of RB 555. The ordering sequence for the definition of the REGs may alsobe referred to as frequency first, time second ordering.

If when defining REs into a REG, the end of a column of a RB is reached,such as in column 5 of RB 555, additional RE(s) of RB 557 may be used asneeded to finish defining the REG. Similarly, at the end of column 5 ofRB 557, two REs (shown as REs 559) are defined into a REG, leaving theREG short by two REs. The two REs may be defined from the top of column6 of RB 555 (shown as REs 561). The definition of REs into REGs maycontinue with the remainder of REs in RB 555 and RB 557, resulting in aninteger number of REGs and no unused REs.

FIG. 5d illustrates a fourth configuration 575 for specifying REGs fromREs over two RBs. Fourth configuration 575 comprises two RBs (RB 580 andRB 582) that are not necessarily logically arranged in any particularmanner.

Definition of REs into REGs may follow as shown in FIG. 4 (i.e., columnorder within individual RBs) resulting in two REs being undefined asREGs at the end of RB 580 (shown as REs 584) and two REs being undefinedas REGs at the end of RB 582 (shown as REs 586). REs 584 and REs 586 maybe referred to as previously undefined REs and may be used to define anadditional REG. As an example, REs 584 and REs 586 may then be used todefine a single additional REG, resulting in an integer number of REGsand no unused REs.

The following discussion relates to the solution where REGs are definedover 2 RBs. REGs are used for defining the mapping of relay controlchannels to REs.

A REG is represented by the index pair (k′, l′) of the RE with thelowest index k in the group with all REs in the group having the samevalue of l. The set of REs (k,l) in a REG depends on the number ofconfigured CRS, CSI-RS and muted REs, as described below withk₀=n_(PRB)·N_(sc) ^(RB×)2, 0≦n_(PRB)<N_(RB) ^(DL)/2.

In the first OFDM symbol of the first slot in a subframe the two REGs inphysical resource block n_(PRB) consist of REs (k, l=0) with k=k₀+0,k₀+1, . . . k₀+5 and k=k₀+6, k₀+7, . . . , k₀+11, respectively.

In the second OFDM symbol of the first slot in a subframe in case of oneor two CRS configured, the three REGs in physical resource block n_(PRB)consist of REs (k, l=1) with k=k₀+0, k₀+1, . . . , k₀+3, k=k₀+4, k₀+5, .. . , k₀+7 and k=k₀+8, k₀+9, . . . , k₀+11, respectively.

In the second OFDM symbol of the first slot in a subframe in case offour CRS configured, the two REGs in physical resource block consist ofREs (k, l=1) with k=k₀+0, k₀+1, . . . , k₀+5 and k=k₀+6, k₀+7, . . . ,k₀+11, respectively.

In the third OFDM symbol of the first slot in a subframe, the three REGsin physical resource block n_(PRB) consist of REs (k, l=2) with k=k₀+0,k₀+1, . . . , k₀+3, k=k₀+4, k₀+5, . . . , k₀+7 and k=k₀+8, k₀+9, . . . ,k₀+11, respectively.

In the fourth OFDM symbol of the first slot in a subframe in case ofnormal cyclic prefix, the three REGs in physical resource block n_(PRB)consist of REs (k, l=3) with k=k₀+0, k₀+1, . . . , k₀+3, k=k₀+4, k₀+5, .. . , k₀+7 and k=k₀+8, k₀+9, . . . , k₀+11, respectively.

In the fourth OFDM symbol of the first slot in a subframe in case ofextended cyclic prefix, the two REGs in physical resource block n_(PRB)consist of REs (k, l=3) with k=k₀+0, k₀+1, . . . , k₀+5 and k=k₀+6,k₀+7, . . . , k₀+11, respectively.

Mapping of a symbol-quadruplet (z(i), z(i+1), z(i+2), z(i+3)) onto a REGrepresented by RE (k′, l′) is may be specified such that elements z(i)are mapped to RE (k, l) of the REG not used for CRS, CSI-RS and mutedREs, in increasing order of i and k . It is noted that the muted REs maybe used to transmit other zero power signals, such as zero power CRS,and the like, not just zero power CSI-RS.

In case a single CRS is configured, CRS may be assumed to be present onantenna ports 0 and 1 for the purpose of mapping a symbol-quadruplet toa REG, otherwise the number of CRS may be assumed equal to the actualnumber of antenna ports used for CRS.

In case one or two CSI-RS are configured, CSI-RS may be assumed to bepresent on antenna ports 15, 16, 17 and 18 for the purpose of mapping asymbol-quadruplet to a REG, otherwise the number of CSI-RS may beassumed equal to the actual number of antenna ports used for CSI-RS.

The UE or relay node may not make any assumptions about REs assumed tobe reserved for RS but not used for transmission of a RS.

In OFDM symbols that contain CRS, the six REGs in virtual resource blockpair (n_(PRB), n_(PRB)+1) consist of REs k=k₀, k₀+1, . . . , k₀+5,k=k₀+6, k₀+7, . . . , k₀+11, k=k₀+12, k₀+13, . . . , k₀+17, k=k₀+18,k₀+19, . . . , k₀+23, respectively.

In OFDM symbols that contain CSI-RS and no muted REs, when 8 CSI-RSports are configured in normal and extended cyclic prefix, the four REGsin virtual resource block pair (n_(PRB), n_(PRB)+1) consist of REs k=k₀,k₀+1, . . . , k₀+5, k=k₀+6, k₀+7, . . . , k₀+11, k=k₀+12, k₀+13, . . . ,k₀+17, k=k₀+18, k₀+19, . . . , k₀+23, respectively, for normal andcyclic prefix.

In OFDM symbols that contain CSI-RS and no muted REs, when 1, 2 or 4CSI-RS ports are configured, the five REGs in virtual resource blockpair (n_(PRB), n_(PRB)+1) consist of REs shown in Tables 1 and 2 fornormal and extended cyclic prefix, respectively.

TABLE 1 2 or 4 CSI-RS are configured in normal cyclic prefix 1-port and4-port CSI-RS 2-port CSI-RS configuration configuration REGs in virtualin normal in normal resource block pair cyclic prefix cyclic prefix(n_(PRB), n_(PRB) + 1) 0 0, 10 k = k₀, k₀ + 1, . . . , k₀ + 4 k = k₀ +5, k₀ + 6, . . . , k₀ + 8 k = k₀ + 9, k₀ + 10, . . . , k₀ + 13 k = k₀ +14, k₀ + 15, . . . , k₀ + 18 k = k₀ + 19, k₀ + 20, . . . , k₀ + 23 1 1,12 k = k₀, k₀ + 1, . . . , k₀ + 3 k = k₀ + 4, k₀ + 5, . . . , k₀ + 8 k =k₀ + 9, k₀ + 10, . . . , k₀ + 13 k = k₀ + 14, k₀ + 15, . . . , k₀ + 18 k= k₀ + 19, k₀ + 20, . . . , k₀ + 23 2 2, 14 3 3, 16 4 4, 18 5 5, 11 k =k₀, k₀ + 1, . . . , k₀ + 4 k = k₀ + 5, k₀ + 6, . . . , k₀ + 9 k = k₀ +10, k₀ + 11, . . . , k₀ + 13 k = k₀ + 14, k₀ + 15, . . . , k₀ + 18 k =k₀ + 19, k₀ + 20, . . . , k₀ + 23 6 6, 13 7 7, 15 8 8, 17 9 9, 19 20 20,26  21 21, 27  22 22, 28  23 23, 29  24 24, 30  25 25, 31 

TABLE 2 2 or 4 CSI-RS are configured in extended cyclic prefix 4-portCSI-RS 2-port CSI-RS REGs in virtual configuration in configuration inresource block pair extended cyclic prefix extended cyclic prefix(n_(PRB), n_(PRB) + 1) 0 0, 8 1 1, 9 2  2, 12 3  3, 13 4  4, 10 5  5, 116  6, 14 7  7, 15 16 16, 22 17 17, 23 18 18, 24 19 19, 25 20 20, 26 2121, 27

In OFDM symbols that contain muted REs corresponding to N mutingconfigurations and no CSI-RS, there are 6-N REGs in virtual resourceblock pair (n_(PRB), n_(PRB)+1), where 0<N<7. A REG contains 4 REs thatare not muted, and none or some muted REs, such that a REG starts at thesubcarrier following the end of the previous REG, and ends with anon-muted RE (unless there are no remaining non-muted REs and in the RBpair but there are remaining muted REs, in which case these are includedin the last REG). REGs in virtual resource block pair (n_(PRB),n_(PRB)+1) are defined in increasing order of subcarriers, starting fromk=k₀.

In OFDM symbols that contain both CSI-RS and muted REs corresponding toN muting configurations, when 8 CSI-RS ports are configured, there are4-N REGs in virtual resource block pair (n_(PRB), n_(PRB)+1), where0<N<5. A REG contains 4 REs that are not muted and not used for CSI-RS,and none or some muted RE, and none or some REs that contain CSI-RS,such that a REG starts at the subcarrier following the end of theprevious REG, and ends with a non-muted RE not used for CSI-RS (unlessthere are no remaining non-muted REs not used for CSI-RS and in the RBpair but there are remaining muted REs or CSI-RS, in which case theseare included in the last REG). REGs in virtual resource block pair(n_(PRB), n_(PRB)+1) are defined in increasing order of subcarriers,starting from k=k₀.

In OFDM symbols that contain both CSI-RS and muted REs corresponding toN muting configurations, when 4 CSI-RS ports are configured, there are5-N REGs in virtual resource block pair (n_(PRB), n_(PRB)+1), where 0<N<6. A REG contains 4 REs that are not muted and not used for CSI-RS, andnone or some muted REs, and none or some REs that contain CSI-RS, suchthat a REG starts at the subcarrier following the end of the previousREG, and ends with a non-muted RE not used for CSI-RS (unless there areno remaining non-muted REs not used for CSI-RS and in the RB pair butthere are remaining muted REs or CSI-RS, in which case these areincluded in the last REG). REGs in virtual resource block pair (n_(PRB),n_(PRB)+1) are defined in increasing order of subcarriers, starting fromk=k₀.

In OFDM symbols that contain both CSI-RS and muted REs corresponding toN muting configurations, when one or two CSI-RS ports are configured,there are 5-N REGs in virtual resource block pair (n_(PRB), n_(PRB)+1),where 0<N <6. Four CSI-RS ports may be assumed to be present on antennaports 15, 16, 17 and 18, corresponding to the 4-port CSI-RSconfiguration which contains the configured CSI-RS configuration withone or two ports.

For reference, the RAN1#62bis agreement on CSI-RS configurations will bediscussed. CSI-RS configuration to (k′, l′) indices are shown below.CSI-RS patterns were agreed based on 3GPP R1-104263.

TABLE 6.10.5.2-1 Mapping from CSI configuration to (k′ ,l′) for normalcyclic prefix. Number of CSI-RS configured CSI 2 4 8 Config- n_(s) n_(s)n_(s) uration (k′ ,l′) mod 2 (k′ ,l′) mod 2 (k′ ,l′) mod 2 Frame 0 (9,5)0 (9,5) 0 (9,5) 0 struc- 1 (11,2)  1 (11,2)  1 (11,2)  1 ture 2 (9,2) 1(9,2) 1 (9,2) 1 type 3 (7,2) 1 (7,2) 1 (7,2) 1 1 4 (9,5) 1 (9,5) 1 (9,5)1 and 5 (8,5) 0 (8,5) 0 2 6 (10,2)  1 (10,2)  1 7 (8,2) 1 (8,2) 1 8(6,2) 1 (6,2) 1 9 (8,5) 1 (8,5) 1 10 (3,5) 0 11 (2,5) 0 12 (5,2) 1 13(4,2) 1 14 (3,2) 1 15 (2,2) 1 16 (1,2) 1 17 (0,2) 1 18 (3,5) 1 19 (2,5)1 Frame 20 (11,1)  1 (11,1)  1 (11,1)  1 struc- 21 (9,1) 1 (9,1) 1 (9,1)1 ture 22 (7,1) 1 (7,1) 1 (7,1) 1 type 2 23 (10,1)  1 (10,1)  1 only 24(8,1) 1 (8,1) 1 25 (6,1) 1 (6,1) 1 26 (5,1) 1 27 (4,1) 1 28 (3,1) 1 29(2,1) 1 30 (1,1) 1 31 (0,1) 1

TABLE 6.10.5.2-2 Mapping from CSI configuration to (k′ ,l′) for extendedcyclic prefix. Number of CSI-RS configured CSI 2 4 8 Config- n_(s) n_(s)n_(s) uration (k′ ,l′) mod 2 (k′ ,l′) mod 2 (k′ ,l′) mod 2 Frame 0(11,4)  0 (11,4)  0 (11,4)  0 struc- 1 (9,4) 0 (9,4) 0 (9,4) 0 ture 2(10,4)  1 (10,4)  1 (10,4)  1 type 3 (9,4) 1 (9,4) 1 (9,4) 1 1 4 (5,4) 0(5,4) 0 and 5 (3,4) 0 (3,4) 0 2 6 (4,4) 1 (4,4) 1 7 (3,4) 1 (3,4) 1 8(8,4) 0 9 (6,4) 0 10 (2,4) 0 11 (0,4) 0 12 (7,4) 1 13 (6,4) 1 14 (1,4) 115 (0,4) 1 Frame 16 (11,1)  1 (11,1)  1 (11,1)  1 struc- 17 (10,1)  1(10,1)  1 (10,1)  1 ture 18 (9,1) 1 (9,1) 1 (9,1) 1 type 19 (5,1) 1(5,1) 1 2 20 (4,1) 1 (4,1) 1 only 21 (3,1) 1 (3,1) 1 22 (8,1) 1 23 (7,1)1 24 (6,1) 1 25 (2,1) 1 26 (1,1) 1 27 (0,1) 1

According to an example embodiment, the definition of REGs may bemodified so that a REG may be defined over one RB in order to ensurethat all REs are allocated to REGs. The definition of a REG over one RBmay be expressed as principle (referred to herein as principle P″):

Ensure that the number of available REs after excluding overhead for RSor zero power REs is a multiple of 4.

Although the discussion focuses on specifying REGs over a single RB, theexample embodiments presented herein may be operable with other numbersof RBs, for example, one, two, three, four, and the like. Therefore, thefocus on one RB should not be construed as being limiting to either thescope or the spirit of the example embodiments.

Principle P″ may impose a number of restrictions. For example, if theCSI-RS in a cell is defined for eight antenna ports, and muting isallowed, then the UE may assume that the number of muted CSI-RS ports isa multiple of two. The number of muted CSI-RS ports (as well asinformation regarding which ones are muted) may need to be signaled tothe UE, over higher layer signaling, as an example.

In addition to the reserved RE(s) (e.g., already reserved in thetechnical or industrial standard), additional RE(s) available in the RBmay be blocked from being used in REGs to ensure that the numberrequirement for REs is met to form a positive integer value of REGs inthe RB. The blocked RE(s) are thus prohibited, along with the reservedRE(s) from being used in the REGs and, as such, they may be used as areserved RE or for other purposes, e.g., transmitting data, referencesignals, interference estimation, power boosting of signals in otherREs, zero power transmitted to reduce interference to signals in thesame position of other UEs/UEs of other cells and the like. Sinceblocked RE(s) may not be used to form a REG, blocked RE(s) may becomeadditional reserved RE(s), and thereafter may be referred to as reservedRE's along with the RE's originally reserved or defined as reserved RE'sunder the applicable industrial or technical standard.

FIG. 6a illustrates a RB 600 with two CSI-RS ports and two reserved(blocked) REs. With two CSI-RS ports, RB 600 includes two REs that areused for the CSI-RS, RE 605 and RE 607. However, the use of RE 605 andRE 607 for the CSI-RS means that the number of REs that are availablefor REG definition is not a multiple of four, hence there may be anon-integer number of REGs or there may be some REs that are notallocated. Therefore, to ensure that the number of REs available for REGdefinition is a multiple of four, two REs in RB 600 may be reserved(blocked) (shown as RE 609 and RE 611). RE 609 and RE 611 may bereferred to as reserved (blocked) REs and may be REs that ordinarily maybe used to carry data (or R-PDCCHs as well as other control messages)but may be specifically prevented from being used to form REGs to ensurethat the number of REs available for REG definition is a multiple offour.

With the two REs used for CSI-RS and two reserved (blocked) REs, thenumber of REs available for REG definition is a multiple of four,therefore, there is an integer number of REGs and there may be no wastedREs if the reserved (blocked) REs are used for some other purpose, suchas transmitting data, reference signals, interference estimation, powerboosting of signals in other REs, zero power transmitted to reduceinterference to signals in the same position of other UEs/UEs of othercells and the like.

FIG. 6b illustrates a RB 620 with two CSI-RS ports and six reserved(blocked) REs. With two CSI-RS ports, RB 620 includes two REs that areused for the CSI-RS, RE 625 and RE 607. However, the use of RE 625 andRE 627 for the CSI-RS means that the number of REs that are availablefor REG allocation is not a multiple of four, hence there may be anon-integer number of REGs or there may be some REs that are notallocated. Therefore, to ensure that the number of REs available for REGallocation is a multiple of four, six REs in RB 620 may be reserved(blocked) (shown as RE 629, RE 631, RE 633, RE 635, RE 637, and RE 639).

With the two REs used for CSI-RS and six reserved (blocked) REs, RB 620may have the appearance of having eight CSI-RS ports. The number of REsavailable for REG definition is a multiple of four, therefore, there isan integer number of REGs and there may be no wasted REs.

FIG. 6c illustrates a RB 640 with four CSI-RS ports and no reserved(blocked) REs. With four CSI-RS ports, RB 640 includes four REs that areused for the CSI-RS, RE 645, RE 647, RE 649, and RE 651. Since thenumber of REs that are available for REG definition is a multiple offour, there may be an integer number of REGs with no unallocated REs.Hence, no reserved REs may be needed.

FIG. 6d illustrates a RB 660 with four CSI-RS ports and four reserved(blocked) REs. With four CSI-RS ports, RB 660 includes four REs that areused for the CSI-RS, RE 665, RE 667, RE 669, and RE 671. However, withthe addition of four reserved (blocked) REs, RE 673, RE 675, RE 677, andRE 679, RB 660 may have the appearance of having eight CSI-RS ports.Since the number of REs available for REG definition is a multiple offour, there may be an integer number of REGs with no unallocated REs.

FIG. 6e illustrates a RB 680 with eight CSI-RS ports and no reserved(blocked) REs. With eight CSI-RS ports, RB 680 includes eight REs thatare used for CSI-RS, such as RE 685 and RE 687. Therefore, the number ofREs available for REG definition is a multiple of four, and there may bean integer number of REGs with no unallocated REs.

In general, a REG is represented by the index pair (k,l) of the RE withthe lowest index k in the group with all REs in the REG having the samevalue of l. The number of REs (k,l) in a REG for mapping of R-PDCCH isalways 4 after discounting the REs configured for CSI-RS transmissionand/or configured for RE muting, and/or the CRS. When CSI-RS areconfigured, 4 or 8 CSI-RS are assumed for discounting the REs formapping of control channels to REs; when muting REs are configured,multiple of 2 4-port CSI-RS should be configured.

The set of REs (k,l) in a REG depends on the number of CRS, CSI-RS andmuted REs configured as described below with k₀=n_(PRB)·N_(sc) ^(RB),0≦n_(PRB)<N_(RB) ^(DL).

In the case CRS are configured, in the first or fifth OFDM symbol of thefirst or second slot in a subframe the two REGs in physical resourceblock n_(PRB) consist of REs (k, l=0) or (k, l=4) or (k, l=7) or (k,l=11) with k=k₀+0, k₀+1, . . . , k₀+5 and k=k₀+6, k₀+7, . . . , k₀+11,respectively.

In the second OFDM symbol of the first or second slot in a subframe incase of one or two CRS configured, the three REGs in physical resourceblock n_(PRB) consist of REs (k, l=1) or (k, l=8) with k=k₀+0, k₀+1, . .. , k₀+3, k=k₀+4, k₀+5, . . . , k₀+7 and k=k₀+8, k₀+9, . . . , k₀+11,respectively.

In the second OFDM symbol of the first or second slot in a subframe incase of four CRS configured, the two REGs in physical resource blockn_(PRB) consist of REs (k, l=1) or (k, l=8) with k=k₀+0, k₀+1, . . . ,k₀+5 and k=k₀+6, k₀+7, . . . , k₀+11, respectively.

In the third OFDM symbol of the first slot in a subframe, the three REGsin physical resource block n_(PRB) consist of REs (k, l=2) with k=k₀+0,k₀+1, . . . , k₀+3, k=k₀+4, k₀+5, . . . , k₀+7 and k=k₀+8, k₀+9, . . . ,k₀+11, respectively.

In the fourth OFDM symbol of the first slot in a subframe in case ofnormal cyclic prefix, the three REGs in physical resource block n_(PRB)consist of REs (k, l=3) with k=k₀+0, k₀+1, . . . , k₀+3, k=k₀+4, k₀+5, .. . , k₀+7 and k=k₀+8, k₀+9, . . . , k₀+11, respectively.

In the fourth OFDM symbol of the first slot in a subframe in case ofextended cyclic prefix, the two REGs in physical resource block n_(PRB)consist of REs (k, l=3) with k=k₀+0, k₀+1, . . . , k₀+5 and k=k₀+6,k₀+7, . . . , k₀+11, respectively.

In the OFDM symbol when CSI-RS are transmitted, and/or REs are muted.For muting, there are the following agreements in the RAN1#62bismeeting.

Muting configuration is cell-specific and signaled via higher-layersignaling. PDSCH muting is performed over a bandwidth that follows thesame rule as the CSI-RS.

A UE may assume downlink CSI-RS Energy Per RE (EPRE) is constant acrossthe downlink system bandwidth and constant across all subframes untildifferent CSI-RS information is received.

The intra-subframe location of muted REs is indicated by a 16-bitbitmap. Each bit corresponds to a 4-port CSI-RS configuration. All REsused in a 4-port CSI-RS configuration set to 1 are muted (zero powerassumed at UE), except for the CSI-RS REs if they belong to this CSI-RSconfiguration. This signaling is common for FDD and TDD CSI-RSconfigurations.

Thus muting can be set by 4-port CSI-RS configuration. Then the set ofREs (k,l) in a REG is as described herein.

In the sixth or seventh OFDM symbol of the first slot or second slot ina subframe, or third or fourth OFDM symbol of the second slot in asubframe in case of 1, 2, 4, or 8 CSI-RS configured or 2 4-port CSI-RSmuting configured, the two REGs in physical resource block n_(PRB)consist of REs (k, l=5) or (k, l=6) or (k, l=12) or (k, l=13) or (k,l=9) or (k, l=10) with k =k₀+0, k₀+1, . . . , k₀+5 and k=k₀+6, k₀+7, . .. , k₀+11, respectively. An illustration is shown in FIGS. 7a and 7 b.

In the third or fourth OFDM symbol of the second slot in a subframe incase of 1,2,4,8 CSI-RS and 2 4-port CSI-RS configured or 4 4-port CSI-RSconfigured, the one REG in physical resource block n_(PRB) consist ofREs (k, l=9) or (k, l=10) with k=k₀+0, k₀+1, . . . , . . . , k₀+11. Anillustration is shown in FIGS. 8a and 8b , illustrating a situation whenCSI-RS are not transmitted, and REs are not muted.

In the sixth or seventh OFDM symbol of the first or 2^(nd) slot, or inthe third or fourth OFDM symbol of the second slot in a subframe in caseof no CSI-RS configured or no muting REs configured, the three REGs inphysical resource block n_(PRB) consist of REs (k, l=5) or (k, l=6) or(k, l=9) or (k, l=10) or (k, l=12) or (k, l=13) with k=k₀+0, k₀+1, . . ., k₀+3, k=k₀+4, k₀+5, . . . , k₀+7 and k=k₀+8, k₀+9, . . . , k₀+11,respectively. An illustration is shown in FIG. 9.

Mapping of a symbol-quadruplet (z(i), z(i+1), z(i+2), z(i+3)) onto a REGrepresented by RE (k′,l′) is defined such that elements z(i) are mappedto RE (k,l) of the REG not used for CRS in increasing order of i and k.In case a single CRS is configured, CRS may be assumed to be present onantenna ports 0 and 1 for the purpose of mapping a symbol-quadruplet toa REG, otherwise the number of CRS may be assumed equal to the actualnumber of antenna ports used for CRS. The UE does not make anyassumptions about REs assumed to be reserved for RS but not used fortransmission of a RS.

According to an example embodiment, in situations wherein two RBs ormultiples of two RBs may be available for use in transmitting themultiple R-PDCCHs, principle P′ may be used to specify the REGs that areavailable for assignment in transmitting the R-PDCCHs.

According to an example embodiment, in situations wherein one or moreRBs are available for use in transmitting the multiple R-PDCCHs,principle P″ may be used to specify the REGs that are available forassignment in transmitting the R-PDCCHs.

FIG. 10 illustrates a flow diagram of communications controlleroperations 1000 in interleaving multiple control messages, such asR-PDCCHs, to REGs of one or more RBs. Communications controlleroperations 1000 may be indicative of operations occurring in acommunications controller, such as an eNB, a low power cell, and thelike, as the communications controller interleaves multiple controlmessages onto one or more RBs.

Communications controller operations 1000 may begin with thecommunications controller specifying (or defining) REGs from REs ofRB(s) per selected principle to form a pool of unused REGs (block 1005).Depending on communications system configuration, such as a number ofCSI-RS ports used per RB, a number of RBs available, and the like, thecommunications controller may select either principle P′ or principle P″to specify REGs from REs. As an example, if only one RB is available totransmit the multiple control messages, then the communicationscontroller may select principle P″ to specify REG from REs. While, iftwo RBs are available to transmit the multiple control messages, thenthe communications controller may select either principle P′ orprinciple P″ to specify REGs from REs. Furthermore, if principle P′ isselected to specify the REGs from REs, the communications controller mayneed to decide how to logically combine (if at all) the two RBs, e.g.,horizontally placing or vertically stacking, as well as how to allocatethe REs across OFDM symbols.

Alternatively, the principle (either principle P′ or principle P″) maybe selected a priori by an operator of the communications system, atechnical standards definition, and the like. Which ever principle isselected or specified may then be used by the communications controller.Therefore, the communications controller may have no part in selectingthe way in which the REs are allocated to REGs.

The communications controller may select an unassigned control message(or a portion of an unassigned message if the unassigned message islarger than a single REG) to assign to an unused REG from the pool ofunused REGs (block 1010). According to an example embodiment, thecommunications controller may select the unassigned control message froma pool of unassigned control messages. The selection of the unassignedcontrol message may be random, or it may be based on a selectioncriteria. Examples of selection criteria may include age of the controlmessage, priority of the control message, service history of a recipientof the control message, priority of the recipient of the controlmessage, size of the control message, available number of unused REGs inthe pool of unused REGs, and the like. If the unassigned controlmessages are larger than a REG, then additional selection criteria mayinclude if a portion of the unassigned control message already beenassigned.

According to an example embodiment, if the selected unassigned controlmessage is larger than a single REG, then the communications controllermay assign the parts of the selected unassigned control message tomultiple REGs from the pool of unused REGs until the entirety of theselected unassigned control message is assigned.

The selected unassigned control message (or the selected portion of anunassigned control message) may be assigned to an unused REG from thepool of unused REGs (block 1015). The unused REG may be selected fromthe pool of unused REGs based on an interleaving rule or function. Theinterleaving rule may be defined to help improve tolerance to errors,improve frequency diversity, and the like.

According to an example embodiment, the selected unassigned controlmessage may be assigned to REGs distributed throughout the RB(s). Forexample, if the selected unassigned control message is larger than asingle REG, then the different parts of the selected unassigned controlmessage may be assigned to unused REGs that are located at differentparts of the RB to help increase frequency diversity.

The communications controller may perform a check to determine if thereare more unassigned control messages (block 1020). If there are no moreunassigned control messages, then communications controller operations1000 may terminate.

If there are more unassigned control messages, the communicationscontroller may perform a check to determine if there are more unusedREGs in the pool of unused REGs (block 1025). If there are no moreunused REGs, then communications controller operations 1000 mayterminate to begin again when additional unused REGs become available.

If there are more unused REGs, the communications controller may returnto block 1010 to select another unassigned control message (or a portionof an unassigned control message) to assign to an unused REG.

FIG. 11 illustrates a flow diagram of operations 1100 at a device as thedevice receives and processes interleaved control messages. Operations1100 may be indicative of operations occurring at a device, such as a RNor a UE, as the device receives interleaved control messages andprocesses the interleaved control messages to find a control messageintended for the device.

Although the discussion of FIG. 11 focuses on interleaved R-PDCCHs, theexample embodiments discussed herein may be applicable to other forms ofcontrol messages, such as U-PHICHs, U-PDCCHs, E-PDCCH, ePDCCH, frequencydomain extensions of PDCCHs, and the like. Therefore, the discussion ofR-PDCCHs should not be construed as being limiting to either the scopeor the spirit of the example embodiments.

Operations 1100 may begin with the device receiving the interleavedcontrol messages transmitted by a communications controller, i.e., oneor more RBs (block 1105). The interleaved control messages may includecontrol messages intended for a number of devices, not just the devicereceiving the interleaved control messages. The device may decode theinterleaved control messages to produce decoded but still interleavedcontrol messages (block 1110).

The device may then make use of a known definition of REs of RB(s) intoREGs to determine the REGs used to transmit the control messages, aswell as a known interleaving rule or function (or correspondingde-interleaving rule or function) to de-interleave the decoded but stillinterleaved control messages (block 1115). The decoded but stillinterleaved control messages comprise a plurality of REGs, with each REGcontaining at least a portion of a control message. According to anexample embodiment, the communications controller may make use of eitherprinciple P′ if two RBs (or multiples of two RBs) are used to transmitthe control messages or principle P″ if one or more RBs are used totransmit the control messages to determine the specification of REs ofRB(s) into REGs. The use of either principle P′ or principle P″ may bepredetermined by an operator of a communications system or by atechnical standard specification. Hence, the device may be able toreadily determine which principle was used to assign REs of RB(s) toREGs.

According to an example embodiment, the device may use either principleP′ or principle P″ to identify REGs in the decoded but still interleavedcontrol messages. The device may make use of the interleaving rule orfunction (or the corresponding de-interleaving rule or function) toselect REG(s) of a single control message to reconstruct the controlmessages present in the decoded but still interleaved control message,thereby producing a plurality of de-interleaved control messages.

The device may process the plurality of de-interleaved control messagesto find a control message intended for it (block 1120).

FIG. 12 illustrates a diagram of a communications controller 1200.Communications controller 1200 may be an implementation of an eNB, a lowpower node, and the like, of a communications system. Communicationscontroller 1200 may be used to implement various ones of the embodimentsdiscussed herein. As shown in FIG. 12, a transmitter 1205 is configuredto send control channels, messages, information, and the like, and areceiver 1210 is configured to receive messages, information, and thelike. Transmitter 1205 and receiver 1210 may have a wireless interface,a wireline interface, or a combination thereof.

A message generating unit 1220 is configured to generate controlmessages. Message generating unit 1220 may generate control messages bygenerating control data, selection of a modulation and coding scheme(MCS) (as well as an aggregation level if needed), and encoding. Aninterleaving unit 1222 is configured to interleave (e.g., assign andplace) the control messages using a REG as a basic interleaving unit.The REGs may be specified from REs of RB(s) using principle P′ orprinciple P″, which may be predetermined for the communicationscontroller 1200. Interleaving unit 1222 may interleave the controlmessages using an interleaving function, which may also be predeterminedfor the communications device 1200.

A signal generating unit 1224 is configured to generate signals fortransmitting the interleaved control messages. Transmitter 1205 may beused to transmit the signals generated by signal generating unit 1224. Adefining unit 1226 is configured to define the REGs from REs usingprinciple P′ or principle P″. Defining unit 1226 is also configured toassign resource elements to fill the REGs, and block unassigned resourceelements. A memory 1230 is configured to store RE to REG assignmentinformation (e.g., principle P′ or principle P″), interleavingfunction(s), control data for the control messages, and the like.

The elements of communications controller 1200 may be implemented asspecific hardware logic blocks. In an alternative, the elements ofcommunications controller 1200 may be implemented as software executingin a processor, controller, application specific integrated circuit, andthe like. In yet another alternative, the elements of communicationscontroller 1200 may be implemented as a combination of software and/orhardware.

As an example, transmitter 1205 and receiver 1210 may be implemented asa specific hardware block, while message generating unit 1220,interleaving unit 1222, signal generating unit 1224, and defining unit1226 may be software modules executing in a processor 1215, amicroprocessor, a digital signal processor, a custom circuit, or acustom compiled logic array of a field programmable logic array.

FIG. 13 illustrates a diagram of a communications device 1300.Communications device 1300 may be an implementation of an RN, a UE, andthe like, of a communications system. Communications device 1300 may beused to implement various ones of the embodiments discussed herein. Asshown in FIG. 13, a transmitter 1305 is configured to send controlchannels, messages, information, and the like, and a receiver 1310 isconfigured to receive messages, information, and the like. Transmitter1305 and receiver 1310 may have a wireless interface, a wirelineinterface, or a combination thereof.

A signal processing unit 1320 is configured to provide processing, suchas decoding, to interleaved control signals received by communicationsdevice 1300. A de-interleaving unit 1322 is configured to de-interleavethe decoded but still interleaved control messages provided by signalprocessing unit 1320. De-interleaving unit 1322 may make use of a REG asa basic interleaving unit. The REGs may be specified from REs of RB(s)using principle P′ or principle P″, which may be predetermined for thecommunications device 1300. De-interleaving unit 1322 may also make useof an interleaving function (or a corresponding de-interleavingfunction) to de-interleave the decoded but still interleaved controlmessages.

A message processing unit 1324 is configured to process a controlmessage intended for communications device 1300. A defining unit 1326 isconfigured to define the REGs from REs using principle P′ or principleP″. A memory 1330 is configured to store RE to REG assignmentinformation (e.g., principle P′ or principle P″), de-interleavingfunction(s), control data for the control messages, and the like.

The elements of communications device 1300 may be implemented asspecific hardware logic blocks. In an alternative, the elements ofcommunications device 1300 may be implemented as software executing in aprocessor, controller, application specific integrated circuit, and thelike. In yet another alternative, the elements of communications device1300 may be implemented as a combination of software and/or hardware.

As an example, transmitter 1305 and receiver 1310 may be implemented asa specific hardware block, while signal processing unit 1320,de-interleaving unit 1322, message processing unit 1324, and definingunit 1326 may be software modules executing in a processor 1315, amicroprocessor, a digital signal processor, a custom circuit, or acustom compiled logic array of a field programmable logic array.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. A method for operating a communicationscontroller, the method comprising: defining a positive integer quantityof control channel resource element groups in a data region of aresource block, the resource block having a number of resource elements,the number of resource elements comprising reserved resource elements,wherein one or more of the reserved resource elements are muted;assigning a plurality of available resource elements to fill in each ofthe positive integer quantity of control channel resource elementgroups; interleaving a plurality of control messages onto the positiveinteger quantity of control channel resource element groups; andtransmitting the positive integer quantity of control channel resourceelement groups.
 2. The method of claim 1, further comprising indicatingthe one or more of the reserved resource elements that are muted byradio resource control signaling.
 3. The method of claim 1, wherein themuted resource elements are muted channel state information-referencesignals (CSI-RS), and wherein the positive integer quantity of controlchannel resource element groups exclude any resource elements mapped toreference signals.
 4. The method of claim 1, wherein interleaving theplurality of control messages comprises mapping each control message inthe plurality of control messages to at least one respective resourceelement group in the positive integer quantity of control channelresource element groups.
 5. The method of claim 4, wherein a firstcontrol message is larger than a single resource element group, andwherein the mapping comprises: partitioning the first control messageinto a plurality of control message units, each equal to or less than aresource block group in information capacity; and mapping the pluralityof control message units to the positive integer quantity of controlchannel resource element groups.
 6. The method of claim 1, whereinassigning the plurality of available resource elements comprisingassigning the plurality of available resource elements with a samenumber of available resource elements in each resource element group,wherein every resource element in the data region of the resource blockis either reserved or assigned.7. The method of claim 1, wherein thereare M reserved resource elements, where M is a positive integer value,and wherein M is a multiple of
 2. 8. A method for operating acommunications device, the method comprising: receiving a resource blockincluding a plurality of control messages interleaved within a positiveinteger quantity of control channel resource element groups defined in adata region of the resource block, the resource block having a number ofresource elements, the number of resource elements comprising reservedresource elements, wherein a plurality of resource elements have beenassigned to fill in each of the positive integer quantity of controlchannel resource element groups, wherein one or more of the reservedresource elements are muted; de-interleaving the plurality of controlmessages from the received resource block; and selecting a controlmessage for the communications device from the plurality of controlmessages.
 9. The method of claim 8, further comprising receiving anindication of the one or more of the reserved resource elements that aremuted by radio resource control signaling.
 10. The method of claim 8,wherein the muted resource elements are muted channel stateinformation-reference signals (CSI-RS), and wherein the positive integerquantity of control channel resource element groups exclude any resourceelements mapped to reference signals.
 11. The method of claim 8, whereinde-interleaving the plurality of control messages is in accordance witha de-interleaving rule.
 12. The method of claim 8, wherein there are Mreserved resource elements, where M is a positive integer value, andwherein M is a multiple of
 2. 13. The method of claim 12, wherein M isequal to
 8. 14. A communications device comprising: a receiverconfigured to receive a resource block including a plurality of controlmessages interleaved within a positive integer quantity of controlchannel resource element groups defined in a data region of the resourceblock, the resource block having a number of resource elements, thenumber of resource elements comprising reserved resource elements,wherein a plurality of resource elements have been assigned to fill ineach of the positive integer quantity of control channel resourceelement groups, wherein one or more reserved resource elements aremuted, and wherein the positive integer quantity of control channelresource element groups exclude any resource elements mapped toreference signals; and a processor coupled to the receiver, theprocessor configured to de-interleave the plurality of control messagesfrom the received resource block, and to select a control message forthe communications device from the plurality of control messages. 15.The communications device of claim 14, wherein the receiver is furtherconfigured to receive an indication of the one or more of the reservedresource elements that are muted by radio resource control signaling.16. The communications device of claim 14, wherein there are M reservedresource elements, where M is a positive integer value, and wherein M isa multiple of
 2. 17. The communications device of claim 14, wherein M isequal to
 8. 18. The communications device of claim 14, whereinde-interleaving the plurality of control messages is in accordance witha de-interleaving rule.
 19. The communications device of claim 14,wherein the muted resource elements are muted channel stateinformation-reference signals (CSI-RS).
 20. The communication device ofclaim 14, wherein the plurality of resource elements have been assignedwith a same number of available resource elements in each resourceelement group.